For integrated circuit fabrication, a semiconductor structure is formed with multiple layers of conductive material to allow for a multi-level interconnecting between devices formed on the semiconductor structure. A connection to one of these conductive layers is achieved by etching a via opening through the dielectric structure and to the desired conductive layer. Conventional etching processes use carbon fluoride based gases, such as CF.sub.4 or CHF.sub.3, to etch the via opening into the semiconductor structure in order to form a metal contact in the via opening at the desired conductive layer. However, the etching process leaves a residual layer on the exposed conductive layer of the semiconductor structure that adds a resistance within the via opening.
The conventional approach to remove the residual layer from the conductive layer within the via opening is to introduce wet chemicals at the semiconductor structure in order to clean off the residual layer. This wet chemical process is costly and inserts toxic materials that raise environmental concerns. Further, the wet chemical process is not effective for small device fabrication due to the decreasing size of the via opening. Therefore, it is desirable to have a cleanup process that is less expensive, environmentally desirable, and suitable for small device fabrication.